1. Field of the Invention
The present invention relates to a scale, having magnetic elements of different magnetization, which are arranged in the measuring direction, and wherein the scale is put together from several base bodies, each base body having several of the magnetic elements on a non-magnetizable support, and wherein the magnetic elements of a base body are magnetized in a single identical direction, and the combined scale has alternatingly a magnetic element of one base body and a magnetic element of another base body in the measuring direction. The present invention furthermore relates to a method for producing such a scale. Finally, the present invention also relates to a position measuring system employing such a scale.
2. Discussion of Related Art
Scales of this type are employed in position measuring systems of processing machines for measuring the relative position of a tool with respect to a workpiece to be processed, as well as in coordinate-measuring machines for detecting the position and dimensions of test objects. In the course of this, the position measuring system can be employed as a direct measuring system, i.e. installed directly on the components to be measured, or as an indirect measuring system, i.e. installed on the drive mechanisms (electrical drive motors). Further applications are found in connection with motor vehicles, for example as steering angle sensors, and in office communications.
A scale is known from EP 0 715 151 B1, which is formed by assembling two identical base bodies. Each one of these base bodies has several magnetic elements magnetized in the same direction. When assembled, the magnetic elements of the one base body lie in the spaces between the magnetic elements of the other base body, so that the scale alternatingly has a magnetic element of one body and of a further body in the measuring direction. In the assembled state, the magnetic elements of the one base body are magnetized in the opposite direction from the magnetic elements of the other base body.
For achieving a zero-symmetrical magnetic field at the surface to be scanned for a position measurement, it is proposed to injection-mold the magnetic elements onto a disk-shaped non-magnetic support by a dual-component injection-molding process.
However, this has the disadvantage that the non-magnetic support is arranged on a surface of the scale which is to be scanned, which results in a reduced magnetic field strength at the scanning location.